[Andrew Blair]

Haha, it must be something with mentors, ours is having more fun than we are I think! We send the shirts at about 80- 100 psi, no regulator. We're just watching the gauge right now, but intend to use a pressure sensor in a bit.
What we've found, although it's still in it's infant stages, is that you begin to drop off with distance increasing after about 80 psi. You get about 3-5 yards further with that extra 20 psi, but thats it. Might be the weight of the shirt. But boy is it accurate. We can consistently put it into about a 3 yard circle at 30 yards. Its pretty fun to see is load the thing though: we use a shovel handle and ram the thing down in for a nice tight seal. It looks like you're seriously loading a cannon. The place where we fire it is on an access road behind our school that gets quite a bit of traffic, teacher and otherwise. We get some awful strange looks in the morning! I am considering the ballistics table once we get the thing consistent.